Title : TiO2 Carbon derivatives composite photocatalyst for advanced and affordable wastewater treatment
Abstract:
The quest for novel efficient and affordable wastewater treatment processes brought photocatalysis into the focus. Highly efficient photocatalysis is based on wide band gap semiconductors that can depollute the wastewater even at low pollutant concentrations (at the ppm range) but above the discharge limit. Among the photocatalysts TiO2 is considered as one of the best candidates in the photocatalytic removal of pollutants during the advanced wastewater treatment, due to its stability in the aqueous media and its lack of toxicity. However, the wide band gap of TiO2 makes its activation possible only when using UV radiation. This is why, the challenge to develop up-scalable and affordable processes lead to the development of various solutions, based on composite layers that make the TiO2 component VIS-active; one of the recent attempts is to develop TiO2-graphene composite structures that support a better charge separation and reduce the electron-hole recombination in TiO2, thus better supporting the photocatalytic reaction mechanism. These composites are mostly reported to be obtained using sol-gel or hydrothermal synthesis, but this paper will report on thin composite layers of TiO2 and reduced graphene oxide (rGO) obtained by Spray Pyrolysis Deposition. The thin films are further tested in the methylene blue removal (according to the standard ISO 10678; 2010) and the results show that the process runs with promising efficiency when irradiated with solar radiation (irradiance higher then 600 W/m2). The influence of the synthesis conditions is investigated and the results show the optimum rGO content in the composite is of 1%. As the composite photocatalyst needs only solar radiation, the process is affordable and the results can be used also in developing self-cleaning coatings with similar composition.
